From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4837C433E1 for ; Tue, 19 May 2020 20:00:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B89AE2065F for ; Tue, 19 May 2020 20:00:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728662AbgESUAb (ORCPT ); Tue, 19 May 2020 16:00:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728359AbgEST7H (ORCPT ); Tue, 19 May 2020 15:59:07 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FAC0C08C5C0; Tue, 19 May 2020 12:59:07 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jb8OF-0000FW-1m; Tue, 19 May 2020 21:59:03 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 7CD5B1C04E3; Tue, 19 May 2020 21:58:48 +0200 (CEST) Date: Tue, 19 May 2020 19:58:48 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] tracing: Provide lockdep less trace_hardirqs_on/off() variants Cc: Thomas Gleixner , Alexandre Chartre , Peter Zijlstra , x86 , LKML In-Reply-To: <20200505134100.270771162@linutronix.de> References: <20200505134100.270771162@linutronix.de> MIME-Version: 1.0 Message-ID: <158991832840.17951.9965229788112577467.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/entry branch of tip: Commit-ID: 0995a5dfbe49badff78e78761fb66f46579f2f9a Gitweb: https://git.kernel.org/tip/0995a5dfbe49badff78e78761fb66f46579f2f9a Author: Thomas Gleixner AuthorDate: Wed, 04 Mar 2020 13:09:50 +01:00 Committer: Thomas Gleixner CommitterDate: Tue, 19 May 2020 15:47:21 +02:00 tracing: Provide lockdep less trace_hardirqs_on/off() variants trace_hardirqs_on/off() is only partially safe vs. RCU idle. The tracer core itself is safe, but the resulting tracepoints can be utilized by e.g. BPF which is unsafe. Provide variants which do not contain the lockdep invocation so the lockdep and tracer invocations can be split at the call site and placed properly. This is required because lockdep needs to be aware of the state before switching away from RCU idle and after switching to RCU idle because these transitions can take locks. As these code pathes are going to be non-instrumentable the tracer can be invoked after RCU is turned on and before the switch to RCU idle. So for these new variants there is no need to invoke the rcuidle aware tracer functions. Name them so they match the lockdep counterparts. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134100.270771162@linutronix.de --- include/linux/irqflags.h | 4 +++- kernel/trace/trace_preemptirq.c | 37 ++++++++++++++++++++++++++++++++- 2 files changed, 41 insertions(+) diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 61a9ced..f150e69 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -29,6 +29,8 @@ #endif #ifdef CONFIG_TRACE_IRQFLAGS + extern void trace_hardirqs_on_prepare(void); + extern void trace_hardirqs_off_prepare(void); extern void trace_hardirqs_on(void); extern void trace_hardirqs_off(void); # define lockdep_hardirq_context(p) ((p)->hardirq_context) @@ -96,6 +98,8 @@ do { \ } while (0) #else +# define trace_hardirqs_on_prepare() do { } while (0) +# define trace_hardirqs_off_prepare() do { } while (0) # define trace_hardirqs_on() do { } while (0) # define trace_hardirqs_off() do { } while (0) # define lockdep_hardirq_context(p) 0 diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c index 4d8e99f..c008801 100644 --- a/kernel/trace/trace_preemptirq.c +++ b/kernel/trace/trace_preemptirq.c @@ -19,6 +19,24 @@ /* Per-cpu variable to prevent redundant calls when IRQs already off */ static DEFINE_PER_CPU(int, tracing_irq_cpu); +/* + * Like trace_hardirqs_on() but without the lockdep invocation. This is + * used in the low level entry code where the ordering vs. RCU is important + * and lockdep uses a staged approach which splits the lockdep hardirq + * tracking into a RCU on and a RCU off section. + */ +void trace_hardirqs_on_prepare(void) +{ + if (this_cpu_read(tracing_irq_cpu)) { + if (!in_nmi()) + trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1); + tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); + this_cpu_write(tracing_irq_cpu, 0); + } +} +EXPORT_SYMBOL(trace_hardirqs_on_prepare); +NOKPROBE_SYMBOL(trace_hardirqs_on_prepare); + void trace_hardirqs_on(void) { if (this_cpu_read(tracing_irq_cpu)) { @@ -33,6 +51,25 @@ void trace_hardirqs_on(void) EXPORT_SYMBOL(trace_hardirqs_on); NOKPROBE_SYMBOL(trace_hardirqs_on); +/* + * Like trace_hardirqs_off() but without the lockdep invocation. This is + * used in the low level entry code where the ordering vs. RCU is important + * and lockdep uses a staged approach which splits the lockdep hardirq + * tracking into a RCU on and a RCU off section. + */ +void trace_hardirqs_off_prepare(void) +{ + if (!this_cpu_read(tracing_irq_cpu)) { + this_cpu_write(tracing_irq_cpu, 1); + tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); + if (!in_nmi()) + trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1); + } + +} +EXPORT_SYMBOL(trace_hardirqs_off_prepare); +NOKPROBE_SYMBOL(trace_hardirqs_off_prepare); + void trace_hardirqs_off(void) { if (!this_cpu_read(tracing_irq_cpu)) {